European Union Enlargement Commissioner Stefan Fuele has warned Turkish Prime Minister Recep Tayyip Erdogan that using excessive force against demonstrators "has no place" in a democracy.

Fuele spoke on June 7 at an Istanbul conference that included Erdogan and he used his speech to voice concerns about a police crackdown on protesters earlier this week. At least three people have died in the ensuing unrest and thousands have been injured.

"What is important now is not only to launch a swift and transparent investigation [into the violence surrounding the protests] but to also to bring those responsible to account," he said.

The EU official maintained that peaceful demonstrations are a "legitimate way" to express views in a democratic society.

In responding to Fuele's comments, Erdogan referred to his administration's "sadness about the intervention at the beginning of those events."

"We already said we will do what is necessary," he said. "Our Interior Ministry is continuing to work on that process. If anyone in a European country carried out these kinds of violent acts and destruction they would face a harsher intervention."

Erdogan claimed he was "open-hearted to anyone with democratic demands," but he added that the peaceful protest had been hijacked by people with a separate agenda.

"If you look at what is happening, people who are manipulating those events because of their political agenda are placing themselves ahead of others who are really asking for their democratic rights," he said.

Erdogan added that: "What we are against is terrorism, violence, vandalism and actions that threaten others for the sake of freedoms."

Tens of thousands of demonstrators have protested across Turkey since last week against what they consider Erdogan's increasingly autocratic and Islamic-rooted rule.

The protests were initially sparked by opposition to a development project in an Istanbul park.